The investigator hypothesizes that children who have hypoglycemia during a period of acute stress represent a unique population which has a high incidence of disorders of glucose metabolism; that patients incidntally found with hypoglycemia during a catabolic gastrointestinal illness, that routine testing usually obtained fails to diffentiate those ewith endocrinopathies or metabolic problems from patients with physiologic hypoglycemia; and that pathologic and treatable causes of aberrant glucose metabolism are under-diagnosed and represent a significant portion of incidental hypoglycemia in the emergency department setting. The investigators will perform a metabolic and endorinologic evaluation of subjects found with unexplained blood sugars less then 50mg/dL. Blood and urine samples will be analyzed for fatty acid oxidation defects along with hormonal deficiencies in order to identify treatable causes of abnormal glucose metabolism. Background: Hypoglycemia in infants and children presents a diagnostic challenge for clinicians due to the difficulty in distinguishing normal physiologic hypoglycemia due to the lack of intake from a pathologic process resulting from the inability of the body to conserve or synthesize glucose. Presently, when a child is incidentally found with a low blood sugar, the hypoglycemia is usually treated with no evaluation performed. The investigators performed a retrospective analysis of incidentally found hypoglycemia (defined as a plasma glucose of less than 50mh/dL) in the emergency room setting. During the period from December 1996-December 1998, hypoglycemia was found in 108 children representing 0.1 percent of emergency room visits. Of these, the low plasma glucose was an incidental finding in 74 patients {age 2.3+/-1.9 years; 65% female ho had no known condition associated with hypoglycemia. The majority of patients had hypoglcyemia in the setting of decreased intake and had gastrointestinal symptoms with an average duration of 2.8+/-1.8 days. Disorders of fatty acid oxidation were subsequently diagnosed in 4/74 (5.4%) subjects even though an evaluation was obtained in concentrations, and anion gap failed to differentiate those subjects who had fatty acide oxidation defects from those with unexplained hypoglycemia.